Are geography journals worth their cost? Refer to the Geoforum (Vol. 37, 2006) study of whether the price of a geography journal is correlated with the quality of the journal, first presented in Exercise 9.29 (p. 501). The data are saved in the GEOJRNL file.
a. In Exercise 9.29a, you fit a straight-line model relating cost (y) to JIF(x). Find and interpret a 95% confidence interval for the slope of the line.
b. In Exercise 9.29b, you fit a straight-line model relating cost (y) to number of citations (x). Find and interpret a 95% confidence interval for the slope of the line.
c. In Exercise 9.29c, you fit a straight-line model relating cost (y) to RPI(x). Find and interpret a 95% confidence interval for the slope of the line.
Exercise 9.29
Are geography journals worth their cost? Refer to the Geoforum (Vol. 37,2006) study of whether the price of a geography journal is correlated with quality, presented in Exercise 2.144 (p. 92). Several quantitative variables were recorded for each in a sample of 28 geography journals: cost of a one-year subscription (dollars); journal impact factor (JIF), the average number of times articles from the journal have been cited; number of citations for the journals over the past five years; and relative price index (RPI). The data for the 28 journals are saved in the GEOJRNL file. Selected observations are listed in the accompanying table.
OJUICE
Run | Sweetness Index | Pectin {ppm) |
1 | 5.2 | 220 |
2 | 5.5 | 227 |
3 | 6.0 | 259 |
4 | 5.9 | 210 |
5 | 5.8 | 224 |
6 | 6.0 | 215 |
7 | 5.8 | 231 |
8 | 5.6 | 268 |
9 | 5.6 | 239 |
10 | 5.9 | 212 |
11 | 5.4 | 410 |
12 | 5.6 | 256 |
13 | 5.8 | 306 |
14 | 5.5 | 259 |
15 | 5.3 | 284 |
16 | 5.3 | 383 |
17 | 5.7 | 271 |
18 | 5.5 | 264 |
19 | 5.7 | 227 |
20 | 5.3 | 263 |
21 | 5.9 | 232 |
22 | 5.8 | 220 |
23 | 5.8 | 246 |
24 | 5.9 | 241 |
Note: The data in the table are authentic. For reasons of confidentiality, the name of the manufacturer cannot be disclosed.
a. Fit a straight-line model relating cost (y) to JIF (x). Give a practical interpretation of the estimated slope of the line.
b. Fit a straight-line model relating cost (y) to number of citations (x). Give a practical interpretation of the estimated slope of the line.
c. Fit a straight-line model relating cost (y) to RPI (x). Give a practical interpretation of the estimated slope of the line.
Exercise 2.144
Are geography journals worth their cost? In Geo forum (Vol. 37,2006), Simon Fraser University professor Nicholas Blomley assessed whether the price of a geography journal is correlated with quality. He collected pricing data (cost for a 1-year subscription, in US dollars) for a sample of 28 geography journals. In addition to cost, three other variables were measured: journal impact factor (JIF), defined as the average number of times articles from the journal have been cited; number of citations for a journal over the past five years; and relative price index (RPI), a measure developed by economists. [Note:A journal with an RPI less than 1.25 is considered a “good value.”] The data for the 28 geography journals are saved in the GEOJRNL file. (Selected observations are shown in the accompanying table.)
a. Construct a scatterplot for the variables JIF and cost. Do you detect a trend?
b. Construct a scatterplot for the variables number of cites and cost. Do you detect a trend?
c. Construct a scatterplot for the variables RPI and cost. Do you detect a trend?
GEOJRNL (Selected observations)
Journal | Cost ($) | JIF | Cites | RPI |
J.Econ.Geogr. | 468 | 3.139 | 207 | 1.16 |
Prog. Hum. Geog. | 624 | 2.943 | 544 | 0.77 |
T.I. Brit. Geogr. | 499 | 2.388 | 249 | 1.11 |
Econ. Geogr. | 90 | 2.325 | 173 | 0.30 |
AAA Geogr. | 698 | 2.115 | 377 | 0.93 |
Geogr. Anal. | 213 | 0.902 | 106 | 0.88 |
Geogr.J. | 223 | 0.857 | 81 | 0.94 |
Appl.Geogr. | 646 | 0.853 | 74 | 3.38 |
Source: Blomley, N. “Is this journal worth US$1118?” Geoforum, Vol. 37,2006.
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